iommu/arm-smmu-v3: Polled IRQs

Because sometimes you really want to know what's going on in spite of
the firmware being rubbish...
Signed-off-by: Robin Murphy <robin.murphy@arm.com>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -33,6 +33,8 @@
 
 #include "arm-smmu-v3.h"
 
+#define ARM_SMMU_TIMER_POLL	ns_to_ktime(NSEC_PER_MSEC)
+
 static bool disable_bypass = true;
 module_param(disable_bypass, bool, 0444);
 MODULE_PARM_DESC(disable_bypass,
@@ -2951,6 +2953,7 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 			dev_warn(smmu->dev, "failed to enable evtq irq\n");
 	} else {
 		dev_warn(smmu->dev, "no evtq irq - events will not be reported!\n");
+		smmu->poll_irq = true;
 	}
 
 	irq = smmu->gerr_irq;
@@ -2961,6 +2964,7 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 			dev_warn(smmu->dev, "failed to enable gerror irq\n");
 	} else {
 		dev_warn(smmu->dev, "no gerr irq - errors will not be reported!\n");
+		smmu->poll_irq = true;
 	}
 
 	if (smmu->features & ARM_SMMU_FEAT_PRI) {
@@ -2980,6 +2984,17 @@ static void arm_smmu_setup_unique_irqs(struct arm_smmu_device *smmu)
 	}
 }
 
+static enum hrtimer_restart arm_smmu_timer_handler(struct hrtimer *hrtimer)
+{
+	struct arm_smmu_device *smmu = container_of(hrtimer, struct arm_smmu_device, hrtimer);
+
+	arm_smmu_gerror_handler(0, smmu);
+	arm_smmu_evtq_thread(0, smmu);
+
+	hrtimer_forward_now(hrtimer, ARM_SMMU_TIMER_POLL);
+	return HRTIMER_RESTART;
+}
+
 static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
 {
 	int ret, irq;
@@ -3009,6 +3024,11 @@ static int arm_smmu_setup_irqs(struct arm_smmu_device *smmu)
 	} else
 		arm_smmu_setup_unique_irqs(smmu);
 
+	if (smmu->poll_irq) {
+		hrtimer_init(&smmu->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+		smmu->hrtimer.function = arm_smmu_timer_handler;
+	}
+
 	if (smmu->features & ARM_SMMU_FEAT_PRI)
 		irqen_flags |= IRQ_CTRL_PRIQ_IRQEN;
 
@@ -3164,6 +3184,9 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
 		return ret;
 	}
 
+	if (smmu->poll_irq)
+		hrtimer_start(&smmu->hrtimer, ARM_SMMU_TIMER_POLL, HRTIMER_MODE_REL);
+
 	return 0;
 }
 
@@ -3608,6 +3631,8 @@ static int arm_smmu_device_remove(struct platform_device *pdev)
 {
 	struct arm_smmu_device *smmu = platform_get_drvdata(pdev);
 
+	if (smmu->poll_irq)
+		hrtimer_cancel(&smmu->hrtimer);
 	arm_smmu_set_bus_ops(NULL);
 	iommu_device_unregister(&smmu->iommu);
 	iommu_device_sysfs_remove(&smmu->iommu);

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -617,6 +617,8 @@ struct arm_smmu_device {
 
 	int				gerr_irq;
 	int				combined_irq;
+	bool				poll_irq;
+	struct hrtimer			hrtimer;
 
 	unsigned long			ias; /* IPA */
 	unsigned long			oas; /* PA */